Think of it this way: if Microsoft had done the same 10 years ago, they would have immediately been sued for abuse of monopolistic position.
And that's the difference: Microsoft had a monopolistic position. Open-source doesn't, so much. What's more, open-source isn't even an organization, so it doesn't even make semantic sense to say that it could have a monopolistic position.
Google (specifically) is a different matter. If they become a monopoly, smack them down. It makes little difference to free/open-source software at large, though.
And that's the difference: Microsoft had a monopolistic position. Open-source doesn't, so much. What's more, open-source isn't even an organization, so it doesn't even make semantic sense to say that it could have a monopolistic position.
Google (specifically) is a different matter. If they become a monopoly, smack them down. It makes little difference to free/open-source software at large, though.